Plant Nutrition

Nutritional needs  Why does grass grow greener where a dog pees?  Why don’t trees pee on dogs? NH 3 animal waste plant nutrient

Nutritional needs  Autotrophic does not mean autonomous  Plants need …  Sun (as an energy source)  Inorganic compounds (as raw building materials)  Water  CO 2  Minerals

Macronutrients  Plants require these nutrients in relatively large amounts  C, O, H, N, P, K, Ca, Mg, S

Macronutrients For what? From where? C macromolecule synthesisCO 2 O macromolecule synthesisCO 2 H macromolecule synthesis & proton pumpsH2OH2O N protein & nucleic acid synthesissoil P nucleic acids, ATP, phospholipidssoil K stomate control, water balancesoil Ca cell wall & membrane structure, regulationsoil Mg chlorophyllsoil S proteins, enzymessoil

Micronutrients  Plants require these nutrients in very small amounts  Cl, Fe, Mn, Bo, Zi, Ni, Mb  Primary cofactors for enzyme function

Nutrient deficiencies  Lack of essential nutrients  Exhibit specific symptoms  Dependent of function of nutrient  Dependent on solubility of nutrient

Magnesium deficiency  Symptoms  Chlorosis = yellowing of leaves  Why? What is magnesium’s function? Take 2 fertilizer pellets & call me in the morning

Chlorophyll Why does magnesium deficiency cause chlorosis? The chlorosis shows up in older leaves first, because plant moves Mg + to newer leaves. Why?

The role of soils  Plants are dependent on soil quality  Texture/structure  Relative amounts of various sized soil particles  Composition  Organic & inorganic chemical components  Fertility

Importance of organic matter  Topsoil  Most important to plant growth  Rich in organic matter  Humus  Decomposing organic material  Breakdown of dead organisms, feces, fallen leaves & other organic refuse by bacteria & fungi  Improves soil texture  Reservoir of minerals  Organisms  1 tsp of topsoil has ~5 billion bacteria living with fungi, algae, protists, insects, earthworms, & nematodes So don ’ t rake your lawn or bag your leaves

Soil of North Carolina  Three most common types:  Cecil soil  Most common  Official state soil of NC  Deep, well-drained soil found in the Piedmont region  Formed from igneous, & metamorphic rock  Sandhill soil  Loose, gray sandy soil  Found in Coastal Plain region  Low in organic matter  Organic soils (histosols)  Typical in wetland areas (marshes, bogs, swamps)  Poor drainage allows organic material to collect over time

Soil health as a global issue  Not taking care of soil health has far-reaching, damaging consequences  1920’s Dust Bowl  Lack of soil conservation  Growing the same crop year after year  Grazing by cattle  Bare ground exposed to wind erosion in winter  Drought  Planting crops in neat rows

Soil health as a global issue  Soil conservation & sustainable agriculture  Maintaining healthy environment  Sustainable production of food supply  Economically viable farming industry contour plowingcrop rotation “A sustainable agriculture does not deplete soils or people.” – Wendell Berry cover crops

Soil health as a global issue  Issues of concern:  Soil fertility  Erosion  Irrigation  Forest destruction

Largest producing countries of agricultural commodities

Fertilizers  “Organic” fertilizers  Manure, compost, fishmeal  “Chemical” fertilizers  Commercially manufactured  N-P-K (ex )  15% nitrogen  10% phosphorus  5% potassium What are the political, economic, environmental issues?

Nitrogen uptake  Nitrates  Plants can only take up nitrate (NO 3 - )  Nitrogen cycle dominated by bacteria  Follow the path of nitrogen fixation What will the plant use N for? root

Soybean root nodules  N fixation by Rhizobium bacteria  Symbiotic relationship with bean family (legumes)

Increasing soil fertility  Cover crops  Growing a field of plants just to plow them under  Usually a legume crop  Taking care of soil health  Puts nitrogen back into the soil Plow it under? Why would you that?

Some plant oddities …

Parasitic plants  Tap into the host plant’s vascular system Rafflesia Mistletoe Indian pipe Dodder

Plants of peat bogs  High acid environment  Most minerals & nutrients bound up & not available to plants  Must find alternate sources of nutrients

Carnivorous plants  Are they really carnivores? Pitcher plant Venus fly trap Sundew

Uses for peat  Peat bogs (mires, moors, muskegs)  Efficient carbon sink  Slow rate of decay  Predominantly Sphagnum moss  Most commonly used for fuel Great conditions for preserving bodies too

Any Questions??